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Rapid alloying of CoCrFeMnNi high-entropy alloy from elemental feedstock toward high-throughput synthesis

《机械工程前沿（英文）》 2023年第18卷第1期 doi: 10.1007/s11465-022-0727-x

摘要： High-entropy alloys (HEAs) are considered alternatives to traditional structural materials because of their superior mechanical, physical, and chemical properties. However, alloy composition combinations are too numerous to explore. Finding a rapid synthesis method to accelerate the development of HEA bulks is imperative. Existing in situ synthesis methods based on additive manufacturing are insufficient for efficiently controlling the uniformity and accuracy of components. In this work, laser powder bed fusion (L-PBF) is adopted for the in situ synthesis of equiatomic CoCrFeMnNi HEA from elemental powder mixtures. High composition accuracy is achieved in parallel with ensuring internal density. The L-PBF-based process parameters are optimized; and two different methods, namely, a multi-melting process and homogenization heat treatment, are adopted to address the problem of incompletely melted Cr particles in the single-melted samples. X-ray diffraction indicates that HEA microstructure can be obtained from elemental powders via L-PBF. In the triple-melted samples, a strong crystallographic texture can be observed through electron backscatter diffraction, with a maximum polar density of 9.92 and a high ultimate tensile strength (UTS) of (735.3 ± 14.1) MPa. The homogenization heat-treated samples appear more like coarse equiaxed grains, with a UTS of (650.8 ± 16.1) MPa and an elongation of (40.2% ± 1.3%). Cellular substructures are also observed in the triple-melted samples, but not in the homogenization heat-treated samples. The differences in mechanical properties primarily originate from the changes in strengthening mechanism. The even and flat fractographic morphologies of the homogenization heat-treated samples represent a more uniform internal microstructure that is different from the complex morphologies of the triple-melted samples. Relative to the multi-melted samples, the homogenization heat-treated samples exhibit better processability, with a smaller composition deviation, i.e., ≤ 0.32 at.%. The two methods presented in this study are expected to have considerable potential for developing HEAs with high composition accuracy and composition flexibility.

关键词： laser powder bed fusion (L-PBF) in situ alloying high-entropy alloys heat treatment rapid synthesis

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Development and application of ex-situ presulfurization technology for hydrotreating catalysts in China

Yulan GAO, Xiangchen FANG, Zhenmin CHENG

《化学科学与工程前沿（英文）》 2011年第5卷第3期页码 287-296 doi: 10.1007/s11705-010-0529-2

摘要： The development and application of ex-situ presulfurization (EPRES) technology for hydrotreating catalysts has been reviewed in the present article. The studies in laboratory scale and commercial practice indicated that the adoption of the EPRES catalyst in industrial application can significantly enhance the degree of presulfurization of metal oxide components, shorten the start-up period, and effectively reduce the environmental impact as well as the danger of start-up procedure in industrial hydrotreating unit. This catalyst has been proved to be versatile for different types of hydrogenation reactions. Different types of active site models are also discussed for better understanding the nature of presulfurized catalysts.

关键词： ex-situ presulfurization in situ presulfurization hydrotreating catalyst sulfur utilization ratio

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一种新的变形高温合金强化方法——磷硼微合金复合强化

胡壮麒,孙文儒,宋洪伟

《中国工程科学》 2005年第7卷第3期页码 17-26

摘要：

阐述了磷、硼的微合金强化作用。磷、硼微合金强化可成倍提高变形合金的持久寿命、降低蠕变速率一个数量级以上。利用磷、硼微合金化技术可发展长寿命高温合金，提高IN718合金的使用温度发展可在700℃长期使用并具有优良性能的涡轮盘合金。

关键词：变形高温合金磷硼微合金化

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双层辉光离子渗金属技术特点

高原,徐晋勇,高清,安晋平,徐重

《中国工程科学》 2008年第10卷第2期页码 26-30

摘要：

分析了双层辉光技术的特点，指出该技术在材料表面合金化方面，是一项适合于高熔点金属表面合金化和采用高熔点金属对铁基或某些熔点较高的有色金属材料进行表面合金化的工艺技术.

关键词：双层辉光离子渗金属技术高熔点金属空心阴极效应阴极溅射扩散

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Polyolefin-nanocomposites with special properties by in-situ polymerization

Walter Kaminsky

《化学科学与工程前沿（英文）》 2018年第12卷第3期页码 555-563 doi: 10.1007/s11705-018-1715-x

摘要：

Exceptionally strong polyolefin nanocomposites are synthesized by in-situ polymerization using soluble metallocene/methylaluminoxane (MAO) as catalysts in a two-step process. First, the soluble metallocene/MAO or other single site catalysts are absorbed on the surface of the nanofillers. Then by addition of ethene or propene, a polyolefin film is formed, covering the nanoparticles, layered silicates, or fibers. The resulting polyethylene and polypropylene nanocomposites are characterized by better physical and chemical properties such as stiffness, gas barrier properties, degradation temperatures, and crystallization rates. They show better mechanical properties than materials produced by mechanical blending. The thickness of the polyolefin can be controlled by the pressure of ethene or propene and by the polymerization time. Carbon fibers and carbon nanotubes are covered with isotactic or syndiotactic polypropylene. Because of the hydrophobic character of the carbon surface, the polymer is drawn on the fiber. This leads to a reinforced combined polymer with special properties. The crystallization temperature is 10 °C higher and therefore the crystallization rate up to 20 times faster than that of pure syndiotactic polypropylene. The form stability increases by 100% if 3 wt-% of carbon nanotubes are incorporated.

关键词： polyolefin nanocomposites metallocenes methylaluminoxane

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Propagation characteristics of transient waves in low-strain integrity testing on cast-in-situ concrete

Hanlong LIU, Xuanming DING

《结构与土木工程前沿（英文）》 2009年第3卷第2期页码 240-240 doi: 10.1007/s11709-009-0100-8

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Thermodynamic analysis of liquid phase in situ hydrogenation of glycerol for 1,3-propanediol synthesis

Kun OUYANG, Yu HUANG, Haoyi CHEN, Tao LI, Fahai CAO, Dingye FANG

《化学科学与工程前沿（英文）》 2011年第5卷第1期页码 67-73 doi: 10.1007/s11705-010-0541-6

摘要： Based on the combination of the glycerol aqueous-phase reforming (APR) and catalytic hydrogenation of glycerol, a novel reaction system of liquid phase in situ hydrogenation of glycerol for the synthesis of 1,3-propanediol is proposed, in which hydrogen is produced from glycerol aqueous-phase reforming in the same reactor. In this new system, the glycerol is the raw material of the aqueous-phase reforming reaction; the hydrogen generated from the APR of glycerol can be quickly transformed to the in situ hydrogenation of glycerol to produce 1,3-propanediol, which can improve the selectivity of hydrogen for the APR process of glycerol. Moreover, thermodynamic calculation of the coupling processes was carried out, and standard molar enthalpies and equilibrium constants of foregoing reactions were obtained. The above calculation results indicate that the combination process is feasible for 1,3-propanediol synthesis.

关键词： glycerol aqueous-phase reforming 1 3-propanediol in-situ reduction

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Mechanical properties of vanadium-alloyed austempered ductile iron for crankshaft applications

《机械工程前沿（英文）》 2023年第18卷第3期 doi: 10.1007/s11465-023-0746-2

摘要： This study focused on the development of austempered ductile iron (ADI) with desirable combination of mechanical properties for crankshaft applications by the combined effect of vanadium (V) alloying and an optimized heat treatment process. The produced unalloyed GGG60, 0.15% V-alloyed GGG60 (V-15), and 0.30% V-alloyed GGG60 samples were subjected to austenitizing at 900 °C for 1 h and subsequent austempering processes at 250, 300, and 350 °C for 15, 30, 60, 90, and 180 min. As a result of these austempering processes, different bainitic structures were obtained, which led to the formation of diverse combinations of mechanical properties. The mechanical properties of the austempered samples were tested comprehensively, and the results were correlated with their microstructures and the stability of the retained austenite phases. From the microstructural observations, the V-alloyed samples exhibited a finer microstructure and a more acicular ferrite phase than unalloyed samples. The V addition delayed the coarsening of the acicular ferrite structures and considerably contributed to the improvement of the mechanical properties of GGG60. Moreover, the X-ray diffraction results revealed that the retained austenite volume and the carbon enrichment of austenite phases in ADI samples were remarkably affected by the addition of vanadium. The increase in volume fraction of retained austenite and its carbon content provided favorable ductility and toughness to V-15, as confirmed by the elongation and impact test results. Consequently, the dual-phase ausferrite microstructure of V-15 that was austempered at 300 °C for 60 min exhibited high strength with substantial ductility and toughness for crankshaft applications.

关键词： austempered ductile iron (ADI) vanadium alloying mechanical properties crankshafts retained austenite

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In situ-based assessment of soil liquefaction potential–Case study of an earth dam in Tunisia

Ikram GUETTAYA,Mohamed Ridha EL OUNI

《结构与土木工程前沿（英文）》 2014年第8卷第4期页码 456-461 doi: 10.1007/s11709-014-0259-5

摘要： The present paper examines the evaluation of liquefaction potential of an earth dam foundation in Tunisia. The assessment of soil liquefaction was made using deterministic and probabilistic simplified procedures developed from several case histories. The data collected from the field investigation performed before and after the vibrocompaction are analyzed and the results are reported. The obtained results show that after vibrocompaction, a significant improvement of the soil resistance reduces the liquefaction potential of the sandy foundation. Indeed, in the untreated layers, the factor of safety drops below 1 which means that the soil is susceptible for liquefaction. However, in the compacted horizons, the values of exceed the unit which justifies the absence of liquefaction hazard of the foundation.

关键词： liquefaction cone penetration test (CPT) standard penetration test (SPT) vibrcompaction sand

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In situ synthesis of FeS/Carbon fibers for the effective removal of Cr(VI) in aqueous solution

Rongrong Zhang, Daohao Li, Jin Sun, Yuqian Cui, Yuanyuan Sun

《环境科学与工程前沿（英文）》 2020年第14卷第4期 doi: 10.1007/s11783-020-1247-8

摘要： Abstract • FeS/carbon fibers were in situ synthesized with Fe-carrageenan hydrogel fiber. • The double helix structure of carrageenan is used to load and disperse Fe. • Pyrolyzing sulfate groups enriched carrageenan-Fe could easily generate FeS. • The adsorption mechanisms include reduction and complexation reaction. Iron sulfide (FeS) nanoparticles (termed FSNs) have attracted much attention for the removal of pollutants due to their high efficiency and low cost, and because they are environmentally friendly. However, issues of agglomeration, transformation, and the loss of active components limit their application. Therefore, this study investigates in situ synthesized FeS/carbon fibers with an Fe-carrageenan biomass as a precursor and nontoxic sulfur source to ascertain the removal efficiency of the fibers. The enrichment of sulfate groups as well as the double-helix structure in ι-carrageenan-Fe could effectively avoid the aggregation and loss of FSNs in practical applications. The obtained FeS/carbon fibers were used to control a Cr(VI) polluted solution, and exhibited a relatively high removal capacity (81.62 mg/g). The main mechanisms included the reduction of FeS, electrostatic adsorption of carbon fibers, and Cr(III)-Fe(III) complexation reaction. The pseudo-second-order kinetic model and Langmuir adsorption model both provided a good fit of the reaction process; hence, the removal process was mainly controlled by chemical adsorption, specifically monolayer adsorption on a uniform surface. Furthermore, co-existing anions, column, and regeneration experiments indicated that the FeS/carbon fibers are a promising remediation material for practical application.

关键词： Carrageenan FeS Double-helix structure Hexavalent chromium

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In-situ condition monitoring of reinforced concrete structures

Sanjeev Kumar VERMA,Sudhir Singh BHADAURIA,Saleem AKHTAR

《结构与土木工程前沿（英文）》 2016年第10卷第4期页码 420-437 doi: 10.1007/s11709-016-0336-z

摘要： Performance of concrete structures is significantly influenced and governed by its durability and resistance to environmental or exposure conditions, apart from its physical strength. It can be monitored, evaluated and predicted through modeling of physical deterioration mechanisms, performance characteristics and parameters and condition monitoring of in situ concrete structures. One such study has been conducted using Non-destructive testing equipment in the city of Bhopal and around located in India. Some selected parameters influencing durability of reinforced concrete (RC) structures such as concrete cover, carbonation depth, chloride concentration, half cell potential and compressive strength have been measured, for establishing correlation among various parameters and age of structures. Effects of concrete cover and compressive strength over the variation of chloride content with time are also investigated.

关键词： concrete carbonation chloride corrosion monitoring models

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面向塑料回收的工业级PP/PE物理合金化技术 Article

瞿金平, 黄照夏, 杨智韬, 张桂珍, 殷小春, 冯彦洪, 何和智, 晋刚, 吴婷, 何光建, 曹贤武

《工程（英文）》 2022年第9卷第2期页码 95-100 doi: 10.1016/j.eng.2021.02.021

摘要：

聚丙烯（PP）和聚乙烯（PE）在日常生活中无处不在。但PP和PE的相容性较差，通过简单熔融共混难以制备具有良好力学性能的合金，为废弃PP、PE的回收再利用带来难题。此外，由于可能存在的环境污染问题，传统的添加相容剂诱导增容的方法也难以得到广泛应用。在本文中，受到中国传统榨油方法的启发，我们报道了一种简单的、可工业化的无添加制备高度取向蜂窝结构PP/PE 二元共混物的新技术。由于独特的蜂窝结构，共混物的力学性能高于其亲系材料，也高于采用传统密炼机制备的样品。因此，本文报道的方法不仅可以应用于不相容聚合物体系的物理增容，也可以为无添加、免分拣的废旧塑料回收提供一种新路径。我们期待通过该技术可以实现废弃塑料环境友好且可持续的循环高值利用。

关键词：聚丙烯聚乙烯物理合金化蜂窝结构

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光学成像中的相位问题 Review

Guo-hai SITU, Hai-chao WANG

《信息与电子工程前沿（英文）》 2017年第18卷第9期页码 1277-1287 doi: 10.1631/FITEE.1700298

摘要：相比于振幅，相位包含更多光场信息。因此，在现代科学和工程学的许多分支中更鼓励测量光场的相位。然而，对可见光波段电磁波而言，直接测量相位非常困难，必须使用计算方法从捕获的光强度中计算相位。本文回顾了近期我们在迭代相位恢复技术及其在光学成像中的应用等方面的研究工作。

关键词：相位恢复；相位成像；计算成像；Gerchberg-Saxton算法；光学加密；计算机全息图

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In situ enhanced bioremediation of dichlorvos by a phyllosphere

Jiying NING, Gang GANG, Zhihui BAI, Qing HU, Hongyan QI, Anzhou MA, Xuliang ZHUAN, Guoqiang ZHUANG

《环境科学与工程前沿（英文）》 2012年第6卷第2期页码 231-237 doi: 10.1007/s11783-011-0316-4

摘要： A bacterium capable of degrading dichlorvos was isolated from the rape phyllosphere and designated YD4. The strain was identified as sp., based on its phenotypic features and 16S rRNA gene sequence. Strain YD4 was able to utilize dichlorvos as the sole source of phosphorus. enhanced bioremediation of dichlorvos by YD4 was hereafter studied. Chlorpyrifos and phoxim could also be degraded by this strain as the sole phosphorus source. A higher degradation rate of dichlorvos was observed after spraying YD4 onto the surface of rape leaves when compared to the sterilized-YD4 and water-treated samples. The results indicated that pesticide-degrading epiphytic bacterium could become a new way for phyllosphere bioremediation where the hostile niche is unsuitable for other pesticide-degrading bacteria isolated from soil and water.

关键词： enhanced bioremediation organophosphorus pesticides phyllosphere Flavobacterium sp.

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Investigate of in situ sludge reduction in sequencing batch biofilm reactor: Performances, mechanisms

Yonglei Wang, Baozhen Liu, Kefeng Zhang, Yongjian Liu, Xuexin Xu, Junqi Jia

《环境科学与工程前沿（英文）》 2018年第12卷第5期 doi: 10.1007/s11783-018-1077-0

摘要：

Microbial metabolism uncoupling, sludge decay is the main mechanism to promote in situ sludge reduction on this biofilm system.

The main reduction mechanism inside the biofilm is sludge decay in the longitudinal distribution of biofilm.

Mizugakiibacter and Azospira anaerobic fermentation bacterium dominate the FSC organisms indicating the dominant mechanism on the biofilm is sludge decay.

The floating spherical carriers with compound of the polyurethane and two fiber balls can effectively blocking suspended sludge, improving Biofilm formation efficiency significantly.

关键词： In situ sludge reduction Biofilm Composite floating spherical carriers Microbial community SBBR